The present invention generally pertains to an overcasting machine for use in sewing insoles to uppers.
Overcasting machines, also often referred to as "overhand sewing", "oversewing", "over-edge sewing" or "overseam sewing" machines, which function to sew insoles to shoe uppers, for example, when manufacturing reversed shoes or shoes wherein the tread is molded or vulcanized onto the insole sewn to the upper, are known in the art as exemplified by German patent No. 1,922,505.
In such prior art machines, an advance disk and a pressure disk are arranged to form a nip, so that the advance disk is driven step-wise and engages the uppers during sewing, while the pressure disk rests against the mated insole material. The advance disk thus drives the material of the upper which in turn at least partially frictionally drives the material of the insole, which engages the freely rotating pressure disk. The pressure disk is spring-loaded towards the advance disk by means of movable support arm rotatably supporting the pressure disk. A tapered blade is used to slightly separate the upper material from the insole material and is movable in the direction of advance of the upper and the insole into a gap at the nip area between the advance disk and the pressure disk, with the sharper edge of the blade pointing in the advance direction to vary the friction driving effect between the upper and insole material, and to produce a gathering of the upper relative to the insole. The blade is mounted on a lever pivotably supported on the machine housing and may be actuated manually, by a pedal or a positioning motor, and cooperates with a stop pin on the machine housing. The blade is adapted to be pivoted into its operational position wherein the lever rests against the stop pin. Then, during the sewing of an insole to an upper, the upper will be gathered, i.e. puckered, in order to compensate for extra width of the upper when sewing is performed along the insole toe and the toe of the upper.
Unfortunately, in such prior art overcasting machines, the blade has a single operating position so that the machine cannot effectively be used to sew diverse upper and insole materials.